Temperature gage going/gone south

[jinman]

The last time I used my tractor, I noticed the temperature gage was hardly registering at all. I thought the thermostat might have stuck open, but did my "test" that the service manager at my dealership told me about. If you ground the lead going to the temperature probe on the engine (with the key ON) the gage should move up and peg out at HOT. In my case, the gage only went half-way up. I have done this test before, so I know the gage is malfunctioning.

Just for fun, I decided to take the instrument pane apart and see if I could find the problem. Well... I got it as far apart as I thought I should and discovered that I would have to do some soldering to remove the gage completely. I will probably do that, but since the gage is working half scale, I can recalibrate my brain for awhile and see if I can find another cheap gage to put into the gage cluster. If I find one, I'll show the modification with pictures. I didn't take any this morning.

So if your temperature gage quits or seems to quit. Jumper the lead going to the temperature probe to ground and see if your gage is failing the same way mine is. I hate having to replace the entire instrument cluster just because one stinkin' gage went bad, but that's what I'll do if I don't come up with a satisfactory work-around.

On the bright side, the instrument cluster is put together quite nicely and is easy to remove. That's makes it an inside job for the workbench. I like that part.

 

[PineRidge]

Jim my temperature gauge also went south months ago. At that time I found out the the gauge module literally plugged into the front side of the PC board. And since I was lucky enough to have another instrument cluster I was able to switch out just the temp gauge with success.

I believe these problems are directly related to the fact that moisture builds up within the cluster itself, and eventually causes problems for the electronics. Have you ever noticed that your instrument cluster fogged in the past?

 

[Soundguy]

Do watch the temps... I wouldn't assume that the gauge is working lineraly on that half scale reading.

I wish you luck on finding a will-fit gauge.

And I'm waiting to see those pics!

soundguy

The last time I used my tractor, I noticed the temperature gage was hardly registering at all. I thought the thermostat might have stuck open, but did my "test" that the service manager at my dealership told me about. If you ground the lead going to the temperature probe on the engine (with the key ON) the gage should move up and peg out at HOT. In my case, the gage only went half-way up. I have done this test before, so I know the gage is malfunctioning.

Just for fun, I decided to take the instrument pane apart and see if I could find the problem. Well... I got it as far apart as I thought I should and discovered that I would have to do some soldering to remove the gage completely. I will probably do that, but since the gage is working half scale, I can recalibrate my brain for awhile and see if I can find another cheap gage to put into the gage cluster. If I find one, I'll show the modification with pictures. I didn't take any this morning.

So if your temperature gage quits or seems to quit. Jumper the lead going to the temperature probe to ground and see if your gage is failing the same way mine is. I hate having to replace the entire instrument cluster just because one stinkin' gage went bad, but that's what I'll do if I don't come up with a satisfactory work-around.

On the bright side, the instrument cluster is put together quite nicely and is easy to remove. That's makes it an inside job for the workbench. I like that part.

 

[jinman]

Jim my temperature gauge also went south months ago. At that time I found out the the gauge module literally plugged into the front side of the PC board.

Mike, I took out the screw on top of the gage face and also the one on the bottom below the foam. Then I saw two solder connections and assumed the gage was soldered in. I never even thought about it unplugging. I guess all I had to do was lift it. Well, that will make installation of another gage a lot easier. I think my gage problem just may be related to heat as much as moisture. I've had some minor fogging, but none in the last few months. The gage worked good up until about a month ago.

Anyhow, thanks for the info. I'll have to take it apart again and see if I can unplug it. Since you say you plugged in your new gage and it worked, I know it's not a problem with the wheatstone bridge circuit. It's probably right in the meter movement.

BTW: That instrument cluster is kinda "slick" the way it's put together. Did you take any pictures when you had yours apart? I don't recall seeing them.

 

[PineRidge]

BTW: That instrument cluster is kinda "slick" the way it's put together. Did you take any pictures when you had yours apart? I don't recall seeing them.

Actually I did but never posted them. Here's a shot of the rear of the temp gauge showing how it plugs into the PC board.

 

[Doc_Bob]

Actually I did but never posted them. Here's a shot of the rear of the temp gauge showing how it plugs into the PC board.

Is there anything you won't take apart ?
Bob

 

[PineRidge]

Is there anything you won't take apart ?
Bob

No, been doing it since I was a kid Bob.

 

[droy]

I will probably do that, but since the gage is working half scale, I can recalibrate my brain for awhile and see if I can find another cheap gage to put into the gage cluster. If I find one, I'll show the modification with pictures. I didn't take any this morning.

Jinman; you may already be aware of this, but when the water temperature gauge quit on my Kenworth eighteen wheeler, I replaced it with another from the dealer. The new gauge showed my motor running about 12 degrees cooler than the old gauge had showed. Puzzled, I contacted an old friend, (independent tractor mechanic, now retired) first thing he said is that if you replace the gauge, replace the sending unit, and be sure they are both the same brand. This is so they will be calibrated to each other. After getting a Kenworth sending unit, and replacing the old one, I noticed it was made a little different, I'm assuming the old one was a Caterpillar brand. Temperature registered where it should, much to my relief. According to friend, sometimes you can get away with just replacing one, but he came across this too often for him to not replace both.
Good Luck!

 

[jinman]

Actually I did but never posted them. Here's a shot of the rear of the temp gauge showing how it plugs into the PC board.

Thanks for the photos. I definitely will be checking out whether I can remove and clean the gage. Since it unplugs, That will make my job easier. I did pull up slightly on the gage, but next time I won't give up as easily.

Droy, that's good advice about the sending unit, but our gages are not very accurate anyhow. There are no numbers on them. They just have a large green, "normal" area and a small red area at the top. I have a mechanical gage with a long probe end. I remove the radiator cap and start the tractor. I let the tractor come up to temperature by running it about 20 minutes and then drop the probe into the radiator cap opening. It gives me a "mark" for where normal temperature is. From what I've seen, if the coolant is up to the correct level. Our tractors are generally around 170º.

EDIT: IF ALL ELSE FAILS, READ THE INSTRUCTIONS! Wow! I feel really silly all of a sudden. For years I've thought and said the instrument panel was a "unit replacement" on our tractors. Finally, I went to my repair manual and found out that is NOT the case. All the gages have individual troubleshooting instructions and different part numbers for replacement. I should be able to order a new temperature gage and replace it. I don't know where I got the idea that it was a unit replacement, but I'm gonna' quit putting out that bogus info in the future.

 

[Soundguy]

Hey.. we'll give you that one fer' free!

Soundguy